1. Field of Invention
The present invention relates to a switching method for communication networks. More particularly, the present invention relates to a switching method between different communication networks for data transmission between portable electronic devices.
2. Description of Related Art
Portable electronic devices have undergone rapid development over the past few years, following advances in software and hardware which have resulted in electronic devices with multi-purpose functionalities. For example, the smart cell phone or the smart personal assistant product integrates the functionalities of the mobile telephone, digital camera and the digital personal assistant into one portable electronic device.
The characteristic of the foregoing portable electronic devices which allows the devices to perform a variety of the application programs similar to a personal computer system, is the ability to use the computer network system and the telephone network system concurrently for communication. The user can choose the communication method of the computer network or the telephone network according to his/her own needs to communicate with another user.
FIG. 1 is a schematic diagram illustrating the communication of the foregoing smart electronic device and other electronic devices. The user 102 uses a smart electronic device 104 to communicate with the user 120 and the smart electronic device 104 has the ability to communicate using the telephone network 106 and the computer network 108. Therefore, the user 102 can choose a suitable network system to communicate with the user 120 according to the device used by the user 120. For example, if the user 120 uses the conventional household telephone 110 or the cell phone 112, then the user 102 must choose the telephone network 106 to communicate with the user 120. If the user 120 uses the conventional personal computer 114, then the user 102 must choose the computer network 108 to communicate with the user 120. If the user 120 uses a smart electronic device 118, then the communication media between the user 102 and the user 120 can be either the telephone network 106 or the computer network 108.
The communication methods and the characteristics of the computer network and the telephone network are different. The advantage of transmitting data via the computer network is that it is more cost-effective. Therefore, in normal conditions, especially when voice communication is used, the first choice for the user to communicate with another user is via the computer network. However, the telephone network range is far more extensive than the computer network and communication via the telephone network is currently more convenient. In the foregoing condition, for example, suppose the user 102 of FIG. 1 uses the smart electronic device 104 to talk to the user 120 on the move via the computer network 108. However, if the user 102 moves to an area not covered by the computer network 108, and then the communication link via the computer network 108 is disconnected, the user 102 must reconnect the smart electronic device 104 to the user 120 via the telephone network 106 in order to continue the voice communication.
Although the Unlicensed Mobile Access (UMA) technique can be implemented in order to solve the foregoing problem, the UMA technique relies on automatically maintaining the communication link on the telephone network or the computer network (in other words, switching between the communication network) to avoid establishing a new communication link. Therefore, the UMA requires an improvement for the entire infrastructure of the telephone network and the computer network, which requires a lot of capital cost and time. For practical uses, the UMA technique still has a lot of areas that can improve.